Drilling structure and bit



Nov. 19, 1935.

F. F. HILL DRILLING STRUCTURE'AND BIT Filed Oct. 22} 1934 BY Z ATTORNEY.

Patented Nov. 19, --1935 UNITED. STATES.

DRILLING STRUCTURE AND BIT Frank F. Hill, Los Angeles, Calif.,

assignor to Union Oil Company of California, Los Angelos, Calif a corporation oi California Application October 22, 1934, Serial No. 749.453

1 Claim. This invention relates to drilling of wells. More I particularly, the invention pertains to the use of novel drilling equipment which will not only eliminate certain expensive operations. but which will also permit the coring of wells, the determination of their inclinations etc. without the necessity of removing the drilling equipment from the well-bore.

I In usual drilling operations the drill bit is suspended on the lower end of a string of drill pipe, the sections of. said pipe being connected to each other by means of couplings or tool-joints. The use of tool-joints is necessary in view of the frequent coupling and uncoupling of pipe, this being essential because of the necessity of periodically withdrawing the string of pipe out of the well" more. Such occasions are, for example, the changing of the drill bit when the latter is worn, the lowering of a core barrel to take a representative sample of the formation, the introduction of an instrument for purposes of orienting the well bore etc. These tool-joints are made in two parts called box and pin members, threaded to each other. The opposite ends of these tool joints are provided with threads or the like for attachment to the individual lengths or joints of pipe. Prior to this invention the pipes used for drilling wells, and more particularly, oil wells, were of the socalled internal upset type, i. e. the ends of such drill pipe were thickened on the interior of the pipe to impart the necessary strength to the pipes at the points carrying the thread. Obviously, such internal upsetting diminished the internal diameter of the pipe at each end of the pipe section. The tool-joints used in connection with the internal upset drill pipe were of such construction that the internal diameters of the tool-joints at their most constricted points were smaller than the'internal diameter of the drill pipe at the parts thereof which are upset. For example, the internal diameter of a four inch drill pipe of the prior art was standardized at 3.826 inches, said-internal diameter decreasing to 2%} inches at the upset ends, and the tool-joints used with such drill pipe had an internal diameter of 2 inches at their most constricted points.

The existence of such constrictions in astring of drill pipe extending several thousand feet into a well-bore resulted in numerous defects. For example, it is well known that. rotary drilling is accompanied by a circulation of mud fluid which is pumped down through the drill pipe. This mud is forced out through openings in the drill bit to lubricate and cool the bit as well as to carry'away the cuttings produced by the drilling operation,

' of the pipe.

The mud fluid and the cuttings rise in the wellbore around the drill pipe. The circulation of mud fluid at a' given rate through a constricted string of drill pipe necessitates considerably higher pressures than the pressures necessary for the cir- I culation of the same fluid at the same rate through a pipe free of constrictions The above mentioned constrictions of the ends 'of the individual pipes and in the tool joints made it impossible to lower core-taking devices through the drill pipe. Each time such operations were to be carried out it was necessary to remove the whole string of pipe out of .the well. These operations are expensive and cumbersome since they necessitate the uncoupling of the string of pipe and setting each strand of pipe on the derrick floor, and the coupling and lowering of the whole string into the well. A further disadvantage in using a.string of pipe having such restrictions in the internal diameter occurs during the so-called fishing operations.

For example, the freezing or sticking of a. drill bit at the bottom of the well-bore sometimes necessitates the cutting off of the drill bit to remove the drill pipe. Since the internal diameters of the tool joint'prevent the lowering of an internal 8 cutter, i. e. one which cuts the pipe from the interior, it is necessary to lower a cutter on the outside of the pipe. This is a very cumbersome and expensive process since the frequent use of rubber protectors, which are used to protect the pipe from wear, necessitates the tearing of all such protectors before the cutter ,may be lowered to a place substantially at the bottom of a well where it is desired to cut the drill pipe. Obviously, such operations include considerable loss of time and money.

It is therefore the main object of the present invention toprovide a structure which eliminates the above and other disadvantages, and to provide a string of drill pipe having a uniform di- 40 ameter throughout its length.

It has now been discovered that the above and other objects may be attained by using drill pipe having a uniform internal diameter throughout its length and by employing tool-joints the smallest internal diameter of which is not substantially less than the internal diameter of such drill pipe. To provide the extra strength at the ends of the drill pipes, which ends are equipped with the threads used for the connecting thereonto of the ends of the tool-joints, the drill pipes used in connection with the present invention are upset externally, the above mentioned threads being cut on such upset portions 6 uniform internal diameter, said string of pipe comprising individual joints of pipe having a uniform internal diameter throughout their lengths, connected to each other -by means of tool-joints having at their narrowest pointsan internal diameterequal to'that of the drill pipe. The invention may further be stated to reside in a string of drill pipe having a uniform internal diameter throughout its length'comprising individual joints of. pipe having a uniform internal diameter, externally upset at their ends, and providedwith threads on such externally upset ends, in combination with tool-joints adapted tobe threaded on said threaded ends' of pipes and said tool-joints having-an internal diameter at their narrowest portions equal to the internal diameter of the drill pipe for which said tool-joints are used as couplings.

.To permit the taking of the deviation of a borehole at its lowermost point, as well as to allow the lowering into the above mentioned type of a drill pipe of a core-barrel for the purpose of recovering a representative sample of the formation' being drilled, it is necessary to extend-the above-described uniform internal diameter both throughout the drill stem and through the bit attached to its lowermost end. It is therefore a still further object. of the present invention to provide a drill bit adapted to drill a well and having a bore along its longitudinal axis substantially equivalent to the internal diameter of drill pipe to which it is attached. A still further object of the present invention is to provide such a drill bit having means therein to receive and hold in position any core-taking or deviation recording instrument.

The'invention therefore also resides in a drill bit adapted to be attached to the lower end of a string of drill pipe, said drill bit having a longitudinal axial bore throughout its length substantially equal to the internal diameter of the drill-pipe to which it is adapted to be attached.

' If so desired, said drill bit may be provided with a plurality of splines along the lower portion of the above mentioned axial bore, said splines being adapted to receive and prevent the further downward movement of any devices, such as core-taking or inclination--indicating or recording instruments lowered through the drill pipe into said-drill bit. In view of the fact that such instruments thuslowered into said drill bit close the lower portion of the bit and thus prevent any circulation of fluid, such as rotary mud, usually employed during drilling operations for the purpose of lubricating the bit and removing the cuttings, the present bit may further be provided with bores parallel to the central bore and opening thereinto at some point in the upper portion of the bit shank.

The cutting means on the lower end of the bit, which constitutes one phase'of the present ting the bit to cut a groove, the outside of which is equal to or slightly greater than the diameter of the shank. The remaining two segments are provided with similar teeth. How-h.

ever, they do not protrude beyondthe lower face of the bit shank, and the hole cut by these teeth has an external diameter substantially equal to the internal diameter of the groove. cut by the first mentioned protruding teeth. It is obvious that the use of the above type of a drill bit causes the downwardly protruding teeth to ilrstcut a shoulder, while the two remaining segments of teeth. break up said shoulder to form the bore. It is also obvious that the above type of a bit actually cuts a cylinder, there being no teeth to break the central core. However, it has been found that the drilling itself and the mud circulation accompanying such drilling cause the breaking of cylinder thus remaining in the central portion of the bore, the {broken core being removed by the circulated mud together with the tain preferred embodiments of the invention are disclosed: Fig. 1 is a diagrammatic view, partly in elevation and partly in section, of the preferred embodiment of the invention, said figure showing a string of drill pipe the individual joints of which are connected by means of tool joints, the string of pipe having a uniform internal diameter throughout its length in combination with the novel type of drill bit described hereinabove;

Fig. 2 is a longitudinal section, on an enlarged scale of one of the tool joints connecting two joints of pipe;

Fig. 3 shows partly in elevation and partly in section a preferred form of the drill bit;

Fig. 4 is a view of the same bit taken at rightouter ends of the tool joint described hereinbelow.

The use of an externally upsetdrill pipe Ill permits a uniform internal diameter of the pipe.

'I'he uppermost joint of drill pipe I0 is connected by means of stool-joint described more fully hereinbelow, to a kelly l3. This kellyv passes through a rotary table I3 and is held therein by means of slips I I". This is well known to those.

skilled in the art. Thus, by means of such an arrangement, it is possible to lower the kelly, and therefore the drill pipe, through the rotary table, said table imparting rotation to the drill bit attached to the lower end of the pipe.

One of ,the tool joints employed for the connecting of the individual joints of pipe is shown in greater detail .11 Fig. 2. As is usual. the tool joint generally indicated by numeral 14 includes pin member IS, and box'member it, each provided at its outer end with a socket ll for receiving the threads I2 of the drill pipe sections or joints it. Each of the sockets ll terminates at its inner end in a reducing shoulder 20 leading to channels 2|, 22 in sleeve portions 22,. 24 of the respective joint members I! and ii. The internal diameters of the channel's 2|, 22 are substantially equal and preferably of the same diameter as the internal diameters of the drill pipe l employed in conjunction with the tool Joints.

The inner end of the box member It includes a tapered socket 26 terminating in a shoulder2l. .This socket is internally threaded as at 28 for cooperation with threads on the pin 30 which constitutes an extension of sleeve portion 24. The base of this pin portion 30 forms a shoulder for the purpose of abutting against the inner end of the box member l6.

With the parts constructed as described and shown in Figs. 1 and 2 the internal diameter throughout the whole string of drill pipe, the individual joints of which are connected by the above type of pin and box tool joints, is uniform throughout. In operation, when it is necessary to withdraw the string of drill pipe out of a well bore the joints are separated by unscrewing threads 28 of the tool joint. The box or pin members are not disconnected from the pipe sections unless the whole structure is to be dismantled. This procedure prevents the destruction of the weaker threaded pipe ends and most of the wear is upon the more rugged box and pin threads. The threads |2 of the lowermost joint of drill pipe ID are threaded into the upper socket of a coupling element 32, the lower socket 33 of which is internally threaded to receive and cooperate with the threaded pin 34 projecting from the upper end of the drill bit 35 shown in detail in Figs, 3, 4 and 5.

The shank 31 of the bit 35 is cylindrical in form and, as stated above, is provided at its upper end with a tapered pin 34 having threads 38 on its outer face, said threads being adapted to cooperate with the threads within socket 33 of the coupling 32. In this manner the bit 35 may be attached to and suspended from the lower end of the drill pipe H) which latter is adapted to be rotated by any usual driving means not shown in the drawing.

The shank 31 and the pin element 34 of the bit 35 are provided with a central longitudinal bore 40 extending the length of the bit is of the same diameter as the bore of the whole pipe structure and is adapted for' the usual circulation of rotary drilling mud. The lower face or the under side of shank 31 is provided with cutting teeth 4| and 42, some of said teeth being disposed so as to cut a shoulder, the outside diameter of which is equal to or slightly greater than the Outside diameter of shank 31, while others are placed so as to break the shoulder cut by the first series of teeth. As shown in the drawing, and more particularly in Fig. thereof, the teeth are aranged in two series, each series comprising two groups of teeth. Each group of teeth of each series is disposed diametrically opposite the group of teeth of the same series, said groups of cutting teeth each covering a quarter section of the lower face of shank 31. The cutting teeth are of the usual form. Teeth 4| are disposed on the lower face of shank 31 and protrude or extend downwardly therefrom.

As arranged these teeth out a shoulder, the outside diameter of which as stated is equal to or slightly greater than the outside diameter of the bit. Teeth 42 are set in within the shank and are disposed further towards the center of the hole thus breaking away the shoulder left by teeth 4|.

Shank 31 is provided with a plurality of bores or mud passages 44 opening at 45 into the upper portion of central bore 40, the opposite ends of bores 44 extending through the lower face of shank 31. These bores 44 are provided for circulationof mud fluid when the lower portion of bore 40 is closed as by means of a core-taking instrument. For the purpose of receiving and holding such a core-taking or deviation and/or recording instrument, shank 31 is provided with splines 46 in the lower portion of bore 40, said splines being tapered off at their upper ends 4] to receive, guide and hold in position any device lowered into the lower portion of such bore 40.

In operation, the individual joints of drill pipe H) are coupled together by means of the above described box and pin tool joints H, the externally up-set drill pipe joints l0 and the channels 2| and 22 of members I5 and |6 of the tool joints is providing a central bore having a uniform internal diameter throughout the string of pipe. The lowermost Joint of pipe threaded into the upper end of coupling 32 the lower end of which carries the above described drill bit 35. As stated above both the coupling 32 and the bit 35 have a bore therethrough having the same internal diameter as that of the string of pipe. The provision of such a uniform internal diameter of the bore is beneficial in that lower pressures may be used for the circulation of mud during drilling operations. The rotation of this string of pipe causes teeth 4| to cut a shoulder, cutting teeth 42, which follow teeth 4|, breaking the shoulder produced by teeth 4|. The circulation of mud through the drill pipe and bores and 44 in the drill bit aid in the breaking up of the core remaining in the center of the bit, the cuttings thus produced being raised to the surface by the circulating rotary mud or similar fluid.

When it is desired to take a core sample or to obtain an indication or record of the inclination of the bore drilled by means of the above described structure, the core-taking or deviationindicating and/or recording instrument may be 40 lowered into the lower part of bore 40 of bit 35 without the necessity of removing the whole string of pipe from the well bore. The instrument thus lowered may have an outside diameter substantially equal to that of bore 40. The coretaking instrument lowered into the above structure may be provided in its lower portion with grooves which are adapted to cooperate with the protruding splines 46, such an arrangement permitting the longitudinal movement of the core barrel but causing the latter to rotate with the drill bit during the core taking operation. During such operations, and because the lower-portion of the drill bit carries the core barrel, the mud circulation is accomplished through bores 44. After the desired length of core is obtained, and if the teeth of the drill bit 35 are still considered-to be sharp enough to continue the drilling operation, the core barrel is removed through the internal bore in the drill string without the necessity of removing the whole string of pipe.

It is thus seen that the above described use of a drill string and drill bit having a bore of a uniform internal diameter eliminates the necessity of carrying out the frequent, cumbersome and expensive operations of withdrawing the drill pipe every time it is desired to take a sample of the formation'or a record of the deviation of the her hole.

This invention is not limited by any theory of its mechanism, nor by any details which have been given merely for purpose of illustration, but is limited only in. and by the following claim which are intended to cover all novelty inherent in the invention:-

I claim: having a substantially uniform internal diameter A drill pipe and cou ling assemblage compristhroughout and being free from constrictions ot ing pipe sections having uniform internal diaminternal diameter less than the internal diameter etcrs and outwardly enlarged and externally of the pipe bore which constrictions would tend 5 threaded end portions and a box and pin type to substantially impedethe flow of material there- 8 coupling connecting said pipe sections, said box, through. pin and pipe sections forming an assemblage FRANKEHIIL. 

